1. Field
The field of the invention is apparatus and methods for drying of brine shrimp cysts, and more particularly such apparatus for final drying and screening of the cysts prior to storage in sealed containers.
2. State of the Art
Brine shrimp cysts are typically harvested from the upper layers of dense concentrated brine found, for example, in the Great Salt Lake of Utah, and are typically harvested by seining and bagging. As originally harvested the cysts are accompanied by lake detritus which must in some fashion be removed by washing and screening. This preliminary cleaning of a harvested mass of shrimp cysts may be accomplished by various methods, which are not the subject of the present invention. Preliminary washing and screening with fine mesh sieves are common. Sometimes, the cysts are finally dewatered, generally after washing with fresh water, by use of centrifugal spin tanks.
After cleaning and dewatering, the cysts must however be further dried before being placed in sealed cans for storage and shipment. Damp masses of cysts may be spread in thin layers in trays and allowed to dry, in either atmospheric or oven environments, often accompanied by manual stirring of the mass of cysts at intervals. Generally, with these procedures, individual cysts cake together into crumbly aggregate. Considerably improved methods and apparatus for the final drying of brine shrimp cysts are found in U.S. Pat. Nos. 4,996,780, 5,088,210 and 5,152,079, which disclose variations in rotating drum devices for final drying of shrimp cysts. Heated air is introduced into the interior of a rotating drum into which the damp cysts are placed. The heated air exits the drum through fine mesh screen covering openings in the drum wall, allowing the passage of air but retaining the cysts within the drum. This method of final drying of the cysts is efficient and produces uncaked shrimp cysts for containerization. It does not, however, have any provisions for separating any broken cysts which may remain. These drum devices are not portable, requiring a permanent on shore installation, preferably within a sheltering building. Since considerable time must elapse between the harvest of the shrimp cysts and the final drying using this method, live viable shrimps which may already have been hatched and harvested along with the eggs typically die and are thus lost to aid in replenishing the shrimp in the body of water. Portability of the final drying apparatus is important, therefore, so that the preliminary cleaning of the harvested shrimp may permit the immediate return of any viable shrimp to the lake. There is therefore an essential need for final cyst drying apparatus which is sufficiently portable to permit practical installation either on the near shore of the body of water or even upon the deck of a shrimp harvesting vessel.